Dense habitation by people, due to inflated land costs, in highrise apartment buildings where living space is small and where hundreds to thousands of such apartments of restricted dimensions are linked together by vast plumbing and pipe connections, has been accompanied by extensive infestations, vertically as well as horizontally, by the genus and species Blatella germanica, commonly known as cockroaches or croton bugs.
Professional exterminators use residual insectidal oils in liquid form and high pressure spraying equivalents to attack this problem. However, due to the close living areas in individual apartments, such efforts to remedy the situation have had to be modified because of the toxicity of the insecticidal chemicals. Many people, particularly women, cannot tolerate the strong pervasive odors of the oils and syncope results. The spraying is directed around the floors adjoining walls which are used by the insects as runways, but such spraying can only be done in carefully aimed, cursory, light amounts. In fact, since these insecticidal residual oils are volatile, their effect wanes within 48 hours but, because of the toxic factor, cannot be used in areas such as china closets, cabinets in kitchens, shelves containing stored foods, or under kitchen and bathroom sinks where all kinds of household necessities such as detergents, cleaning and dusting cloths, soap, toilet paper, drugs, etc. are stored. Thus, the amount of space that can be covered by spraying is minimal. The spraying, therefore, must be frequent and expensive, while the toxicity gradient rises during the first 24 hours thereafter.
Cockroaches abide preferably in moist, dark spaces where they lay their eggs, for example, under sinks, shelves where pots and pans are kept, on plumbing fixtures such as pipes or traps, or on the wall spaces surrounding them. These nests, called egg cases, are only infrequently destroyed by spraying. Breaks in the plaster or cement of walls around the periphery of water pipes, where they are inserted through holes for connections between floors, are frequent at kitchen sinks, wash basins, bathroom toilets and shower connections. Spray nozzles do not reach these breaks. Unfortunately, workmen in construction neglect to secure circular metal shields (known in the plumbing trade as "escutcheons") around pipe holes to block them off because the spaces around traps are narrow and it is a backbreaking job. Through such breaks insects can crawl over pipelines for any number of stories.
Cockroaches lay eggs three times annually, and from each egg case anywhere from 30 to 50 young are hatched each time. These young nymphs are found mostly at floor level, or on lower floors of cabinets, or on shelf space, having traveled from under sinks or pipe connections in search of food. At this stage of life, they are under one millimeter in length and are barely visible to the naked eye. Since the egg cases are adhered to walls or pipes by insect secretion, it is obvious that eliminating them requires a better means than volatile sprays.
As the nymphs grow to adult size (nearly 3/4 inch in length), the adults seek runways, cracks or any other sort of cover when disturbed in the search of food. In the adult stage they are substantially, but not exclusively, night crawlers. When a strong light is turned on, they "freeze" immobile. Light is to them the signal of danger. The nymphs, however, are diurnal crawlers as well and are less sensitive to the danger signal of light. Thus, it becomes apparent that any means directed against the reduction in numbers or the elimination of nymphs is most effective, since 15 to 25 females, when resulting from the hatching of one egg case containing 30 to 50 eggs, can produce 450 to 1,250 nymphs, and this can occur a second time during a year, subject to reduction in numbers only by variant environmental conditions.
One product offered for sale at retail is a small cardboard box which holds about 1/2 ounce of loose foodstuff that is lethal to cockroaches. It is opened at the perforations around a closure tab by finger pressure, whereupon the foodstuff particles pour out on the floor or shelf space, scattering about profusely. This is an effective idea for houses having cellars or attics or detached sheds or barns or outside garbage areas. However, in highrise apartments or inside homes or mobile homes where living space is minimal, it presents some major problems. The foodstuff contacts the fingers when opening the box and in use the particles, which are somewhat toxic to warm-blooded domestic animals, including humans, are strewn over surfaces and areas of floors, shelves, cabinets, etc., where they cannot be readily distinguished from other particulate matter thereon.